This issue has been fixed in the 3.1 branch, and will go out in the upcoming 3.1 beta. As part of this fix process I put together test cases from http://en.wikipedia.org/wiki/HSL_and_HSV#Examples to make sure that we have complete coverage over the color conversion process. This revealed a few other issues such as floating point precision, and our inconsistent handling of arguments passed into HSL vs HSV objects - these have also been changed to be more consistent.